Low tension ignition system including



Dec. 1958 w. B. SMITS LOW TENSION IGNITION SYSTEM INCLUDING LIGHT WEIGHT MAGNETO Filed July 21, 1954 INVENTOR BY m Q ATTORNEY United States Patent LOW TENSION IGNITION SYSTEM INCLUDING r LIGHT WEIGHT MAGNETO Wytze Beye Smits, Voorhurg, Netherlands, assignor to Smitsvonk, N. V., Leidschendam, Netherlands, a company Application July 21, 1954, Serial No. 444,760

3 Claims. c1. s1s--z1s This invention relates to an ignition system for a low tension surface discharge spark plug, and more particularly to a new combination of an ignition system including a light weight magneto.

The general type of system to which the present invention is directed is described in my Patent No. 2,506,472 and in my application Serial No. 167,902, filed June 13, 1950, now abandoned. In this system a condenser is charged to a low voltage, preferably not over 5,000 volts and with an electrical energy of not more than 2 joules. A distributor connects the thus charged condenser to a low tension surface discharge spark plug where the discharge occurs.

In known ignition systems, both low tension and high tension, one spark discharge is created from the energy generated during one half cycle of an alternating current supply. Since the energy of discharge must be high in order to ignite the fuel mixture, a rather large magneto must be used to generate that quantity of energy during one-half cycle.

It is, therefore, the primary object of the present invention to provide an ignition system in which the size of the magneto is materially reduced without sacrificing the electrical energy of the spark discharge.

The primary object of the invention is eifected by arranging the circuitry of the system to charge the condenser through a plurality of half cycles prior to each discharge. Thus, if the energy of discharge must be 2 joules, the magneto of the present invention must generate only joules per half cycle rather than 2 joules per half cycle as in known magnetos; where n is the number of half cycles used to charge the condenser.

It is, therefore, a further object of the invention to provide a low tension condenser discharge ignition system in which the condenser is charged through a plurality of half cycles of the energy-producing magneto before discharge of the condenser across the spark gap.

The foregoing as Well as other objects of the invention will become more readily apparent from a consideration of the detailed description of the invention taken in conjunction with the drawings in which:

Fig. 1 is a schematic circuit diagram of the ignition system according to the present invention; and

Fig. 2 is a diagrammatic view of a mechanical device which may be substituted for the rectifier bridge of Fig. 1.

The principal components of the present ignition system are spark plugs 10, 11, 12 and 13, a distributor 14, a condenser 15, a rectifying arrangement 16, and a magneto 17.

The magneto 17 is of an ordinary type having a rotor 18 and a stator 19. The stator has windings 20 which are connected through leads 21'and 22 to the rectifying arrangement 16.

In the embodiment shown in the drawings, the rectifying arrangement consists of four rectifiers 23', 24, 25 and Patented Dec. 2, 1958 one half cycle of the magneto (one pole change, that is) the current will flow in the direction indicated by the arrow A and in the next half cycle, the current will flow in the direction of the arrow B, in both cases the current flow through the condenser being in the same direction as indicated by the arrows AB above the condenser.

The condenser is connected to the distributor arm 27 of the distributor 14 through an electrical connection 28. When the distributor arm passes any one of the four poles the charge on the condenser is discharged across that pole and across the electrodes of the spark plug associated with that pole.

The distributor arm 27 is mechanically connected through linkage diagrammatically shown at 30, which linkage includes a gear train 31. The linkage between the magneto rotor and the distributor arm is designed to permit the magneto rotor to rotate through a plurality of pole changes between each discharge of the condenser. Assuming in the present case that it is desired to have nine pole changes for discharge, that is it is desired to charge the condenser through nine cycles before eachdischarge, then the reduction gearing 31 should be 6 to 1.

With that example, it can be seen that the magneto need be designed to deliver only one-ninth the power which would be required of a magneto. used with known ignition systems. A magneto delivering :a small fraction of the power normally required during a half cycle obviously can be much smaller and lighter'than magnetos which are now used. The magneto, of course, must rotate much faster than a magneto in a known ignition system, but this is not a difficult requirement to meet in view of the high speeds at which magnetos are now able to run and in view of the fact that the reduction in size of the magneto required will permit the magneto to operate at higher speeds.

It is to be understood that the circuitry and arrangement of parts shown in the drawing and described herein are subject to wide variation without departing from the scope of the invention. For example, the number of poles in the magneto can be varied, the reduction gearing can be varied, the number of cycles before charging the condenser can be varied and the arrangement for directing the charging current through the condenser in the same direction for both cycles need not be the particular rectifier bridge as shown, but rather other arrangements can be used including mechanical means for reversing the leads between the field winding 20 and the condenser 15 with each half cycle.

An example of such a mechanical switching arrangement is shown in Fig. 2 of the drawings. In that figure a field winding 40 is center tapped to ground by connection 41. A condenser 42 is also connected to ground at one side and on the other side is connected to the distributor arm and to two contacts 43 and 44.

Located between the field winding contacts and the tWo condenser contact points 43 and 44 is a rotating member 45 which is driven by the magneto, for example, by some suitable linkage. The rotor 45 is shown in perspective and consists essentially of two electrical connectors 46 and 47 separated by an insulator 48. The connectors 46 and 47 are disposed at right angles to each other.

In operation, the rotor 45 is synchronized with the magneto so that during one half cycle the upper end of the field winding 40 is connected to the condenser through Contact 43 and during the next half cycle the lower end of 'the fieldwinding is connected'to the condenser 42 tical and efficient embodiments of the invention, it should be Well understood that the invention is not limited to such embodiment as there might be changes made in the arrangement, disposition andform of theparts Without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

Iclaim:

1. In a low tensionignition system comprising a condenser, a magneto producing only 1/ 11 part of the energy required to charge said condenser each half cycle, at least one sparkflplug,,a distributor periodically connecting said condenser across said spark plug including a mechanical linkage between said magneto and said distributor for driving said magneto through at least it half cycles for each connection of a spark plug with said condenser, and means connecting said magneto output to said condenser to charge said condenser.in thesame direction for each pole change.

2; Annignition system according to claim 1 in which said last named meanscornprises a rectifier bridge.

3. An ignition system according to claim 1 in,which said last named means comprises mechanicalmeansfor reversing the connections between said magneto andflcondenser every half cycle.

References Cited in the file of this patent UNITED STATES PATENTS 2,433,715 Smart et a1. Dec. 30, 1947 

